Watershed Management

Water Quantity

Provision of an adequate volume of freshwater supply, or water quantity, is a primary concern of hydrologists, planners, and other individuals responsible for water management. While freshwater is globally scarce, its distribution is highly variable, which means that different locations encounter distinctive challenges to provide freshwater supply for human and industrial use. For example, arid regions in the southwestern United States have severe water shortages, while water-rich areas along the Great Lakes (the United States and Canada) have plentiful supply.

In general, management of water quantity is best approached at the drainage basin or watershed scale, which is the extent of land (the catchment area) that channels snowmelt and rain drainage into a waterway. However, water, particularly lakes and rivers, has been traditionally used as a convenient geographic feature of the landscape to divide land into different political boundaries. This means that many watersheds cross political boundaries at different scales. Some examples of transboundary rivers include the Colorado River, which forms part of the boundary of Arizona with Nevada and California, and the Ohio River, which forms the southern boundary of Ohio, Indiana, and Illinois and the northern boundary of West Virginia and Kentucky. Some national boundaries are also formed by rivers, such as the Jordan River, which flows along Syria, Israel, Palestine, and Jordan, or by lakes, such as the Caspian Sea, which borders Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan.

Even if water is not the actual boundary, water also flows through different political boundaries, making the management of water politically challenging. Consider, for example, the Tigris and the Euphrates rivers, which have headwaters in Turkey and flow through Syria and then into Iraq. Depending on their position within the watershed, nations often adopt different views as to how water management should be approached. Turkey views the Tigris and Euphrates system, which is sourced in that country, as a resource that it has the right to contain and has built the Ataturk dam and other smaller dams to manage the flow of water from Turkey into Syria. Downstream, Syria and Iraq argue that they have a right to the water that traditionally flowed through the rivers’ water course and contest Turkey's right to restrict the rivers’ flow north of their borders. In a world with a growing population and an increasing demand for limited water, water management is a real source of conflict, particularly where watersheds cross political boundaries. Indeed, several books have explored the issue of wars over access to water. Even within nations, there can be conflict over how water should be allocated. One recent example in the United States is the dispute between Virginia and Maryland about the right of a growing suburban county in Virginia to access additional water from the Potomac River. That this dispute had to be settled by the U.S. Supreme Court in 2003 demonstrates the intensity of conflict surrounding access to water.

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